**Probability** is simply the **likelihood of an event happening.** It can be expressed in the following ways:

1. Equal Probability

2. Likely Probability

3. Unlikely Probability

4. Certain Probability

5. Impossible Probability

**1. Equal Probability**

**Example:**

There are 2 pens in a bag: one red, and one blue. Since there is one of each, the likelihood of picking a red or a blue pen is **equal,** therefore the probability is equal. There is **1 blue pen out of 2 pens,** or 12 **probability.**

**2. Likely Probability**

**Example:**

Here we have 3 pens: 2 red, 1 blue. Since we have more red pens, the probability of picking out a red **is higher than (likely)** that of picking out a blue. The probability, written out in number form is **2 out of 3,** or 23.

**3. Unlikely Probability**

**Example:**

It's **less likely (unlikely)** that you would pick out a blue pen, since there are more red than blue. The probability of picking out blue would be written as **1 out of 3,** or 13.

**4. Certain Probability**

The word **certain** means that an event will definitely happen without a doubt.

**Example:**

If we had a set of all red balls, we could say that it is **certain** that we would pick out a red ball from this set, since this is the only option.

**5. Impossible Probability**

**Impossible** means that there's no way that event will happen.

**Example:**

Here, we can say that it is **impossible** that a black ball will be picked out because there are no black balls in this set.